The long term goals of this proposal are to facilitate preclinical development of our novel therapeutic strategy for the currently incurable Limb Girdle Muscular Dystrophy Type 2B (LGMD2B). The muscular dystrophies are muscle wasting disorders with increased morbidity and mortality. LGMD2B is caused by dysferlin gene mutations leading to altered protein expression (dysferlinopathy). Deficient repair of damaged membranes via dysferlin-dependent membrane fusion has been implicated. However, lacunae exist in our knowledge of whether dysferlin regulates well-known vesicle fusion related processes (e.g. Acetylcholine Receptor (AChR) recycling &maintenance of synaptic transmission at the neuromuscular junction-NMJ). Using powerful pharmacogenetic tools available in the C. elegans model of LGMD2B, we have identified a novel role for fer-1 in the regulation of NMJ synaptic transmission (Preliminary studies). Our identification of a synaptopathic or myasthenic component has tremendous nosological and translational implications. Interestingly, Acetylcholine Esterase Inhibitors (AChEI) administration improves the survival of the A/J mouse model of LGMD2B in a small pilot trial (Preliminary Studies) and suggests the hypothesis that the NMJ deficit caused by dysferlin deficiency is amenable to treatment using AChEI as a candidate therapeutic to increase the efficiency of neuromuscular transmission and improve LGMD2B outcomes. As a specific aim we propose a well-designed, proof-of-principle study in order to complete the preliminary steps required for successful preclinical development of this candidate therapeutic and test our translational hypothesis. We will undertake a therapeutic trial where we treat 8 month old A/J mice with AChEI for 8 months. Therapeutic potential will be will be assayed using in vivo and ex vivo means to determine improvement of the dystrophic phenotype. The relevance and health relatedness of this project is that undertaking these studies we will ensure clearer understanding of the molecular and functional patho-physiology as well as facilitate preclinical development of our novel therapeutic strategy for LGMD2B. PUBLIC HEALTH RELEVANCE: The health relatedness of this project is that by completion of our aim we will ensure clearer understanding of the molecular and functional patho-physiology of limb-girdle muscular dystrophy Type 2B (LGMD2B) as well as facilitate preclinical development of our novel therapeutic strategy for LGMD2B.